Comparison of monoculture and mixed culture (Scenedesmus obliquus and wild algae) for C, N, and P removal and lipid production

This preliminary study aims to exploit the biomass of microalgae Chlorella vulgaris; Scenedesmus obliquus; and Chlorococcum sp. in the form of a mixed culture as raw material of alternative fuels. Microalgae were cultivated in the artificial growth medium of PHM (Provasoli Haematococcus Media) for 9 days to reach the exponential phase. Hydrolysis was carried out at a temperature variation of (oC) 25; 80; 100; 120; 140; 160 within 30 minutes by adding hydrochloric acid. Biomass fermentation by adding 50% (v/v) Saccharomyces cerevisiae for 5 day to produce alcohol compounds. The last stage is separation of the alcohol compounds from another compounds by distillation. The result showed that carbohydrate levels with color change indicator in luff schoorl solution at hydrolysis and fermentation stages severely were 12.20 mg/L. Carbohydrate levels in fermentation stage produced 17% (v/v) alcohol compounds while in the distillation stage, 98% (v/v) alcohol will be separated into intermediate compounds such as linoleic acid and methyl alcohol as a characteristic of bioethanol. At 80oC of hydrolysis temperature, 58% bioethanol was produced. Further research is needed, since the preliminary study proves the mixed culture of microalgae is potentially to be utilized in producing bioethanol.

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Nutritional value changes in response to temperature, microalgae mono and mixed cultures

Acta Limnologica Brasiliensia ◽

10.1590/s2179-975x7118 ◽

2019 ◽

Vol 31 ◽

Author(s):

Frederico Pacheco Militão ◽

Valéria de Oliveira Fernandes ◽

Kathiani Victor Bastos ◽

Aline Paternostro Martins ◽

Pio Colepicolo ◽

...

Keyword(s):

Fatty Acids ◽

Mixed Culture ◽

Cell Density ◽

Total Lipid ◽

Biochemical Composition ◽

Essential Fatty Acids ◽

Scenedesmus Obliquus ◽

Total Lipid Content ◽

Mixed Cultures ◽

Significant Difference

Abstract Aim The response of mixed cultures and monocultures of Pseudopediastrum boryanum (Turpin) E. Hegewald and Scenedesmus obliquus (Turpin) Kützing was assessed in the laboratory at three different temperatures: 20, 30 and 40 °C. The change in biomass and biochemical composition of these cultures was evaluated. Methods Microalgae were placed in a batch culture over 21-days in ASM1 medium. Cell density was directly counted every two days using a Fuchs-Rosenthal hemocytometer. Chlorophyll ‘a’ and total carotenoids were extracted twice. Protein, carbohydrate, total lipid and fatty acid contents were determined at the end of the experiment. Results Cultures grown in 40 °C exhibited no growth. However, there was increased cell density (13.6 x 106 cell.mL-1) and biomass (55 g.L-1) in the S. obliquus monoculture at 30 °C. High protein concentrations (672.6 mg.g-1) were observed in monocultures P. boryanum and S. obliquus at 20 °C treatments. There were high carbohydrate concentrations (6.17 mg.g-1) in P. boryanum unialgal at 30 °C. There was no significant difference in total lipid content between S. obliquus (95.5 mg.g-1), P. boryanum (96.3 mg.g-1) and the mixed culture at 20 °C (105.3 mg.g-1). FAMEs varied significantly regarding the number of unsaturated components, which predominantly consisted of fatty acids with two or more unsaturated bonds. Conclusions The biomass of the treatments analyzed was rich in proteins and essential fatty acids (such as linolenic acid), yet low in carbohydrate content, suggesting its potential use as a food supplement. Our results indicate that mixed culture of P. boryanum and S. obliquus was inefficient in cultivating biomass or biochemical compounds as compared to the unialgal cultivations. However, algae grown together showed better stability in their biochemical composition in response to changes in temperature, an important factor for microalgae production in open ponds and in food safety measures. These results suggest the consortia among different species of microalgae should be tested to determine better methodologies for the production of biomass and metabolites with greater stability towards environmental factors.

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